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A sample of 81 students has a mean GPA of 3.25.  The sample is normally distributed, and...

A sample of 81 students has a mean GPA of 3.25.  The sample is normally distributed, and the population standard deviation is found to be 0.63 grade points.  Find the Lower Limit of the 95% confidence interval. (express your answers rounded to two decimal places)

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Answer #1

Solution :

Given that,

Sample size = n = 81

Z = 1.645

Margin of error = E = Z* ( /n)

= 1.645 * (0.63 / 81)

Margin of error = E = 0.12

At 95% lower confidence interval estimate of the population mean is,

- E

3.25 - 0.12

3.13

Lower limit: 3.12

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